Let's see who knows their Chevys. "305 vs Chevy 307" which i

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jetsetw31

G-Body Guru
Sep 9, 2010
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Happy Holidays to all. This one is for engine guys. The Chevy 305 vs the Chevy 307, which is the better motor? This is the beginning of my WTH were they thinking series. Let's hear some views on this.
 

jrm81bu

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Jul 9, 2008
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

307 would be the better choice for anything performance related. It has a larger bore than the 305, which is the 305's biggest problem.
 

Fox80

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Jun 27, 2013
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

I agree the 307 is the better choice, the 305's were all emissions era low compression motors. Some 305's have roller cams, but that doesn't offset the junk heads and other components they used in them, some of the late 60's 307 motors used in cars like the Malibus, and Canaro are actually a pretty decent small cubic inch motor
 

chevy2480

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Apr 28, 2010
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

307 are not to be under estimated. My buddy had a 307 in his 85 cutlass and i had a 350 in my 86 same trans and rear. We would always try racing. He would eat me off the line but upper end my 350 would get him. Imo the 307 has torque and a little hp so 307 all day over a dog 305
 

thrasher

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Nov 12, 2013
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

They're both b*st*rd engines. Another depends on what your looking for deal.

Back in the day one of my friends put small tube headers, Performer intake, and a Holley 600vs carb on his 307 equiped 69 Camaro.
It really didn't do squat and I rode in that car plenty. Shortly after he added a Comp Cams 268HE cam. That helped a little on the top end but the thing was still weak as hell.
Later that year he added a set of 4.10 gears and that helped but it was still weak. You could just tell it was lacking something.

The next year he got a good deal from one of his work buddies on a Victor JR and a 650dp. That wasn't really the best move as it killed the bottom end off a little.
So to fix that he put a "Vega" converter in it. That helped but still it wasn't quite right.

Next he finally put the stock set of cast# 186 heads with 194/150 valves that he had on it.
That was the ticket! It came alive and ran great surprising quite a few people after that.
The one thing that had been really holding that engine back was the strangling 172 intake valves. Hell even the 305 got 184's!!!

The Performer RPM wasn't out yet but the Holley 300-36 (Contender/Street Dominator) manifold was.
I sure wish he had tried it but as they say hindsight is 20/20
 

Clone TIE Pilot

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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

Chevy 307, 1968-1973, stock power 115-200 HP.

Chevy 305, 1976-2000, stock power 130-250 HP.

Many 305s have 9.5 to 1 CR which was better than what most engines had in the 70s and 80s.

Unlike the 307, later 305s got some of the nice SBC upgrades such as 1 piece rear seals, center bolt heads, roller cam provisions, and vortec heads.

Only thing aftermarket carbs like Holleys do is make a car lose MPGs for zero gain in power.
 

jetsetw31

G-Body Guru
Sep 9, 2010
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

Well IMHO, The 307 would have been the motor that ruled the 80s. Why? Just think of all the FI systems that were on the 305 throughout the 80s. A similar system on the 307 could have beaten or at least matched the 302 Ford motor that actually ruled the 80s. Even when the 307 was in production it was installed in the entire line up. The engine never had a chance to see any of the personal improvements that were done by Chevy to improve the 305. From Crossfire injection to Throttle body Injection to TPI, the 307 could have been the ringer.
Then I wake up and it's still that !@#$%^* 305!!! :blam:
 

seawolf18

Master Mechanic
Jan 12, 2013
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

clean8485 said:
In what application did you get a 305 that was rated at 250HP?

305 TPI
 

DRIVEN

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Apr 25, 2009
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Re: Let's see who knows their Chevys. "305 vs Chevy 307" whi

305 vs 307? Can't really compare the two. There was never even a mild performance version of the 307. All were 2bbl with low compression ratios. I ran one in my Rambler wagon for a while. Stock (tired) bottom end, 462 heads, mild Comp XE cam, Performer intake and Edelbrock carb. Was great all around cruiser. The carb choice was probably holding me back. It didn't have the off-idle torque of a 305 but everywhere else it pulled stronger.
I would suspect that the 307 would have lived longer if it weren't for emissions standards.
 
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